1. Field of the Invention
The present invention relates to a fixing device and image formation device.
2. Description of the Related Art
In a fixing device of an image formation device such as a printer, a fax machine, or a copier, there is a fixing roller in which a heating source is provided. After the fixing device receives an image formation instruction, it starts to provide the electricity to the heating source so as to preheat the fixing roller. In this preheating process, the surface temperature of the fixing roller may rise, and its temperature rise rate may be represented by a surface temperature rise value of the fixing roller within, for example, 1.5 seconds, i.e., may be represented by a temperature gradient. In a case where a standard voltage is 220 V, if the fixing roller itself works normally, then the temperature gradient of the fixing roller may be greater than or equal to 7 degrees C. If the temperature gradient is less than 7 degrees C., then the image formation device may determine that the fixing roller temperature gradient is abnormal, and after that, may stop heating the fixing roller so as to avoid a hidden danger such as smoking or a paper jam.
The problem that causes the temperature gradient of the fixing roller to be less than 7 degrees C. may be a hardware problem of the fixing roller itself or a circuit malfunction of the image formation device. Due to the hardware problem of the fixing roller itself, the fixing roller cannot be sufficiently heated by the heating source. As a result, the surface temperature rises slowly so that the temperature gradient of the fixing roller is less than 7 degrees C. Accordingly, the image formation device may display the hardware problem on a display interface so as to prompt its user to make a request for repairment. For example, in an area where electrical infrastructure construction is not well done, the electricity cannot be sufficiently supplied; this may result in a low voltage of an electric wireline. In addition, when the electricity is supplied again to the electric wireline after power cut, the electricity may be simultaneously supplied to many apparatuses which worked when the power cut occurred. As a result, electric power demands are getting concentrated at this time; this may result in a short-time low voltage. If the fixing device is started by utilizing this kind of low voltage, then the fixing roller may not be sufficient heated by the heating source, and the temperature gradient may be less than 7 degrees C. Accordingly, this may increase the probability of reporting an error of the image formation device.
However, a conventional image formation device cannot inform its user of the reason for the above-described malfunction without delay. As a result, the user may think that the reason is a hardware problem having occurred in the image formation device. That is to say, perhaps the user will put a lot of effort into finding the reason, or will make a request for repairment. In addition, if the voltage of an electric wireline in the area where the user lives is not stable, then the image formation device may be normally started sometimes, and may be abnormally started sometimes. In this case, the user may think that the quality of the image formation device is not good. That is to say, perhaps the user will make a complaint to the manufacturer of the image formation device. On the other hand, upon receipt of the report, a maintenance worker may carry out detection with respect to the image formation device. However, since the image formation device itself does not have any problem, if the voltage of the electric wireline is restored to normal by the maintenance worker when he carries out the detection, then the image formation device can be started normally. That is to say, the maintenance worker cannot rapidly find the malfunction reason; as a result, perhaps he will have to replace some components. These kinds of problems may not only bring inconvenience to the user and maintenance worker but also increase the after-sale service cost of the manufacturer.